/Engine/Source/Runtime/UMG/Public/Blueprint/UserWidget.h
The system calls this method to notify the widget that a mouse button was pressed within it. This event is bubbled.
Whether the event was handled along with possible requests for the system to take action.
[FEventReply](API\Runtime\UMG\Components\FEventReply) OnMouseButtonDown ( [FGeometry](API\Runtime\SlateCore\Layout\FGeometry) MyGeometry, const [FPointerEvent](API\Runtime\SlateCore\Input\FPointerEvent) & MouseEvent )